Nonaqueous Electrolyte Secondary Batteries

Abstract

The present invention is intended to improve load characteristics at the time of charging or discharging by assuring a lithium ion transport pathway in the crystal structure of olivine lithium-containing manganese phosphate. There is used a positive electrode active material which is a composite material comprising a material having an olivine structure and represented by Li 1-y [Mn 1-x M x ]PzO 4 (0<x≦0.3, −0.05≦y<1, 0.99≦z≦1.03, and M includes at least one of Li, Mg, Ti, Co, Ni, Zr, Nb, Mo or W) and a carbon material, and which shows an average half width of 0.17 or more, and an intensity ratio between a diffraction line near 20° and a diffraction line near 35° of not less than 0.7 and not more than 1.0, in powder X-ray diffractometry.

1 . A nonaqueous electrolyte secondary battery comprising: a positive electrode being capable of undergoing lithium ion intercalation and deintercalation; and a negative electrode being capable of undergoing lithium ion intercalation and deintercalation, which are formed with an electrolyte inserted between them,
 wherein the positive electrode comprises a positive electrode active material,   the positive electrode active material is a composite material comprising a material represented by Li 1-y Mn 1-α PzO 4  (−0.05<α<0.05, −0.05≦y<1, 0.99≦z≦1.03) and a carbon material, and   the ratio of the intensity of a (011) diffraction line near 20° to the intensity of a (131) diffraction line near 35° in powder X-ray diffractometry of the composite material is not less than 0.7 and not more than 0.8.   
     
     
         2 . The nonaqueous electrolyte secondary battery according to  claim 1 , wherein an average half width in the powder X-ray diffractometry of the composite material is not less than 0.16 and not more than 0.18. 
     
     
         3 . The nonaqueous electrolyte secondary battery according to  claim 1 , wherein a carbon content of the composite material is not less than 3 wt % and not more than 7 wt %. 
     
     
         4 . The nonaqueous electrolyte secondary battery according to  claim 1 , wherein the carbon material is a polysaccharide comprising alpha-glucose. 
     
     
         5 . The nonaqueous electrolyte secondary battery according to  claim 1 , wherein the carbon material is dextrin. 
     
     
         6 . A nonaqueous electrolyte secondary battery comprising: a positive electrode being capable of undergoing lithium ion intercalation and deintercalation; and a negative electrode being capable of undergoing lithium ion intercalation and deintercalation, which are formed with an electrolyte inserted between them,
 wherein the positive electrode comprise: a positive electrode combination agent comprising a positive electrode active material and a conductive aid; and a positive electrode current collector,   the positive electrode active material is a composite material comprising a material represented by Li 1-y Mn 1-α PzO 4  (−0.05<α<0.05, −0.05≦y<1, 0.99≦z≦1.03) and a carbon material,   an average half width in powder X-ray diffractometry of the composite material is not less than 0.16 and not more than 0.18,   the ratio of the intensity of a (011) diffraction line near 20° to the intensity of a (131) diffraction line near 35° in the powder X-ray diffractometry of the composite material is not less than 0.7 and not more than 0.8,   the conductive aid is a carbon material, and   a carbon content of the positive electrode combination agent is not less than 5 wt % and not more than 10 wt %.   
     
     
         7 . A nonaqueous electrolyte secondary battery comprising: a positive electrode being capable of undergoing lithium ion intercalation and deintercalation; and a negative electrode being capable of undergoing lithium ion intercalation and deintercalation, which are formed with an electrolyte inserted between them,
 wherein the positive electrode comprises a positive electrode active material,   the positive electrode active material is a composite material comprising a material represented by Li 1-y [Mn 1-x M x ]PzO 4  (0<x≦0.3, −0.05≦y<1, 0.99≦z≦1.03, and M includes at least one of Li, Mg, Ti, Co, Ni, Zr, Nb, Mo or W) and a carbon material,   an average half width in powder X-ray diffractometry of the composite material is not less than 0.16 and not more than 0.18, and   the ratio of the intensity of a (011) diffraction line near 20° to the intensity of a (131) diffraction line near 35° in the powder X-ray diffractometry of the composite material is not less than 0.7 and not more than 1.0.   
     
     
         8 . The nonaqueous electrolyte secondary battery according to  claim 7 , wherein the positive electrode active material is a composite material comprising a material represented by Li 1-y [Mn 1-x1-x2 M1 x1 M2 x2 ]PzO 4  (0<x1+x2≦0.3, 0<x1≦0.25, 0<x2≦0.05, −0.05≦y<1, 0.99≦z≦1.03; M1 includes at least one of Co or Ni, and M2 includes at least one of Mg, Ti, Zr, Nb, Mo or W) and a carbon material. 
     
     
         9 . The nonaqueous electrolyte secondary battery according to  claim 7 , wherein a carbon content of the positive electrode active material is not less than 3 wt % and not more than 7 wt %. 
     
     
         10 . The nonaqueous electrolyte secondary battery according to  claim 7 , wherein a Fe content of the positive electrode active material is 100 ppm or less.